| With the continuous exploitation of energy and the sharp increase in demand for energy,the energy crisis has gradually intensified,which requires all industries to take measures to deal with this problem.In the coal-fired power generation industry,cogeneration units have the characteristics of high energy utilization and low environmental pollution.The widespread use of this type of units and their research on energy saving and consumption reduction are effective responses to energy problems.The study of optimal load dispatch in cogeneration plants can both improve the efficiency of the plant itself and is also important for energy saving and emission reduction.In this paper,the energy consumption characteristics of CHP units and the optimization of load dispatch are taken as the main subjects of research.Firstly,the operating characteristics and the thermal economic indicators of the different heating units in CHP are presented.The total standard coal consumption of the whole plant is selected as the thermal economic indicator and the calculation process is collated and derived.An energy consumption calculation model for the heating unit,i.e.the principle thermal system model,was established based on thermodynamic principles and calculated on the basis of historical operating data of a 350 MW single pump heating unit.The sensitivity coefficient of the selected characteristic parameters is obtained by partial derivative of support vector machine(SVM),and the influencing factors of energy consumption characteristics are analyzed.The results show that load,main steam pressure,main steam flow,reheat cold end steam pressure,reheat steam pressure,external heat supply,main feed water temperature,feed water pump outlet pressure,condenser vacuum degree and reheat steam temperature are the factors that have the greatest influence on energy consumption,which are used as input parameters of least squares support vector machine model.The simulation calculation of THA conditions was compared with historical data to analyze the characteristics of the thermal and economic indexes of the heating unit with the variation of steam extraction.The results show that the heat consumption and coal consumption of the single pumping heating unit are positively proportional to the steam extraction when the electric load is constant,while the heat consumption rate of power generation and the standard coal consumption rate of power generation are inversely proportional to the steam extraction of heating.To ensure the accuracy of the fit,the parameters were pre-processed and the paper used least squares support vector machine(LS-SVM)to regress the collected parameters with high sensitivity coefficients for prediction.The relative error results of the tested samples were all less than 0.05,and the groups with excessive differences were screened out.Based on the operating characteristics of the heating units,the energy consumption characteristic equations were fitted to obtain the energy consumption characteristics.For the load allocation problem of cogeneration units.This paper proposes the use of the particle swarm method to establish an optimal load dispatch model,and also proposes two improved methods for comparison.The dispatch results show that the particle swarm method with compression factors(YSPSO)and the particle swarm method with adaptive weights(SAPSO)have a better optimization effect,and the YSPSO method can reduce up to 4.62 t·h-1compared to the PSO method,providing some ideas for the load dispatch problem of cogeneration.This paper also optimizes the load dispatch with the goal of coal consumption cost.The results show that the particle swarm optimization results in a reduction of approximately30,000 yuan/hour compared to the average load dispatch method.The optimal load dispatch method has certain optimization effects and has practical implications for the economic efficiency and energy saving of power plants. |
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